Don Wilhelm wrote:
The real problem is due to contact bounce at the key contacts.
I agree. I've been successful at using a bug with auto-detect by making
a simple reed relay switch as follows:
Get a radio shack 12 volt SPST reed relay (part no. is 275-233). One
side of the relay coil goes to the positive terminal of a 9v battery and
the other side goes to your key or bug's ungrounded contacts. In
parallel with the coil put a 10 uf 25v electrolytic capacitor (also from
Radio Shack) and any silicon diode. Orient the capactitor so that the
positive side goes to the coil terminal that is connected to the
battery. The diode is reverse-connected; its CATHODE goes to the coil
terminal that is connected to the battery. Finally, connect the
negative side of the battery to the bug's grounded side. If you want to
run the circuit from a 12v supply instead of a battery, put an 820 ohm
1/4w resistor in series with the 12v.
Use a fixed font to view the schematic below:
coil
|------------+@@@@@@@+--------> to key
| | 10uf |
- + +--| (--+
--- - 9v | |
| +--|<---+ diode
|------------------------------>
///
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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